The Next Leap in Wireless Charging

Imagine a world where power traveled through the air to recharge your smartphone

Originally posted by Bree Fowler in Consumer Reports

Illustration of a smartphone using wireless charging

The dream of being able to send an electric current through the air, from one location to another, is not new. It dates back more than a century to the days of Nikola Tesla.

The legendary inventor envisioned a world where energy could be transmitted to wherever it was needed without the use of wires. He built a massive tower and power plant on New York’s Long Island, but the project failed after he ran out of money.

Fast forward to the present day. Tesla’s dream has yet to come true, at least on a commercial scale, but a handful of startup companies say they’re going to make it a reality very soon. 

In the not-too-distant future, you could feasibly roam the earth without ever having to worry about the battery in your smartphone dying. The same goes for the one in your laptop. Your cordless drill and lawn trimmer would never need recharging.

Before we get to that magic moment, however, the technology behind it is likely to surface in less thrilling applications. Entrepreneurs see it powering electronic price tags on store shelves and keeping airport self-flushing toilets, well, flushing.

“I believe in this,” says Florian Bohn, CEO of GuRu Wireless. Bohn, who quit his job as a Caltech scientific researcher to work on the technology, compares the development of wireless power to that of WiFi.

“Twenty years ago, nobody had WiFi," he says. "Now look at all the applications that exist because of it. There are tons of things that will be enabled by this technology, too.”

In fact, at the recent CES gadget show in Las Vegas, a handful of companies showed off what they claim is the next incarnation of wireless power.

Here’s a look at what they’re working on.

Power Through Radio Frequencies

Ossia, which makes power transmitters and receivers under the brand name Cota, has created a digital shelf labeling system for retailers that requires no wires or batteries. The labels, which are currently being tested in some Walmart stores, receive tiny amounts of power and data from transmitters built into ceiling tiles that operate at 2.4 gigahertz. That’s the same radio frequency used by many wireless routers, cordless phones, and Bluetooth.

This allows company officials to raise and lower prices remotely; eliminating the need for employees to replace the stickers and tags on products at each store.

Jennifer Grenz, Ossia’s vice president of marketing, says the system could easily save a company like Walmart millions of dollars in labor costs, allowing for greater flexibility when it comes to pricing changes.

And because the power is stored in supercapacitors instead of batteries, she says, it would prevent the millions of coin cell batteries that currently power such shelves from ending up in landfills.

Traditional radio frequencies are just one of the charging methods wireless power companies are exploring. Some, including GuRu, prefer millimeter wave technology. Others use infrared light.

Experts say all three methods have their pros and cons. In the end, it’s anyone’s guess which one the market may adopt.

Ossia has received Federal Communications Commission approval to use the 2.4 GHz frequency. The downside of that approach is that it lacks the range and directionality of higher frequencies, says Swarun Kumar, an assistant professor of electrical and computer engineering at Carnegie Mellon University in Pittsburgh.

As a result, it’s not as fast and efficient as technologies that send power over higher frequencies such as millimeter wave and infrared light. The farther the waves travel, the more the power dissipates.

On the other hand, Kumar says, the lower frequencies don’t need the clear line of sight that infrared frequencies do and they’re not stopped by the obstructions that hamper millimeter waves.

“It’s all a trade-off,” he says. “It really depends on what you’re trying to accomplish.”

For Ossia’s shelf-charging system to work at 2.4 GHz, it requires a transmitter the size of a ceiling tile, making the system impractical for the average home.

That’s why the company is seeking FCC approval to use the higher 5.8 GHz frequency for the residential wireless power system it showed off at CES. That would allow the company to shrink the transmitter to roughly 1 square foot. While that’s still a large device, it wouldn’t look ridiculous in a living room.

In theory, the transmitter, which has a range of about 30 feet, could power not only smartphones but also any compatible smart home device.

“We’re trying to make it like a WiFi router,” Grenz says. “Stick it in a corner, put the Cota sleeve on your phone and you’re good to go.”

Ossia is looking to license the technology. It already has a partnership agreement in place with the phone case maker Spigen, which plans to develop a case with a built-in Cota receiver.

While that project has hit a few speedbumps since being announced about a year ago, Grez says she expects to see a product sometime this year. 

Power Through Light

For Wi-Charge, the road to wireless power travels straight through the public restroom.

The company is partnering with toilet maker Sloan to put its wireless power system into self-flushing toilets, which often rely on batteries. It has also struck deals with Gojo, the inventors of Purell hand sanitizer, and Hansgrohe, which makes smart faucets.

Yuval Boger, the company’s chief marketing officer, says public restrooms are a natural fit for Wi-Charge’s products. Bathroom operators tend to be reluctant to knock down walls and install electrical systems for electrically powered fixtures.

And so all those hand sanitizer dispensers, sinks with motion detectors, and automatic toilets end up being powered by battery packs that frequently need replacing. And that’s a problem Wi-Charge’s technology, which uses infrared light to send power, is uniquely able to fix, he says.

While sending power through infrared light requires a line of sight, that isn’t a big problem for fixed objects, such as sinks and toilets. And his company’s transmitter is roughly the size of a large lightbulb. It even can be screwed into, and powered by, a spare lamp.

Boger claims Wi-Charge’s system is very safe, too. “It’s just light,” he says. “And light is something you’re exposed to every day.”

While the technology doesn’t require FCC approval, it does need Food and Drug Administration clearance, which Wi-Charge has received.

The company is working on getting its technology into smart shelving in stores, smart door locks, and video doorbells, as well as quick service restaurant stations that allow customers to order food and charge their smartphones.

With a product like a smart door lock, you can add the wireless power technology by swapping out the battery pack without asking consumers to replace the device, Boger says. “Then, over time, we can integrate it into the products themselves.” 

Power Via Robot

GuRu’s Bohn thinks the happy medium between radio frequency and infrared light may lie in the millimeter wave technology used in some 5G wireless communications systems.

Millimeter wave operates at a frequency that falls between those of traditional radio frequencies on the low end and infrared light on the high end. It can’t travel through large obstructions—though Bohn says a phone case shouldn’t be a problem—but it also doesn’t require infrared’s line of sight.

To demonstrate how its millimeter wave power solution works, GuRu created the Rovee, a wireless-power transmitter built on top of a standard robotic vacuum displayed in a little pen at CES.

By moving about your home, the robot could reach more devices, Bohn says.

“With power transmission, you have to be efficient,” he explains. “If some of the waves get blocked or deflected, it decreases efficiency. This is typically why you want a line of sight.”

In addition to Rovee, GuRu showed off a lamp-sized desktop product specifically designed for conference room use with the aim of charging multiple mobile phones simultaneously and a ceiling-mounted unit that can send power across a room to receiver-equipped smartphones, tablets, laptops, or security cameras. Both are meant mainly for industrial or commercial use.

GuRu says it’s in the final stages of getting FCC approval for its products and talking to potential partners, with the hope of bringing a product to market before the end of this year. 

Reality Check

As with any emerging technology, there’s no shortage of hurdles standing in the way of the charging systems offered by these wireless power companies.

Development costs money, and regulatory requirements can create bottlenecks, Kumar says. And success ultimately hinges on getting the big companies that manufacture smartphones, as well as smart home and other battery-operated devices, to integrate the technology into their products.

Boger says consumers could see his technology at work in a commercial setting later this year but predicts it will be several more years before smartphones receive power over the air, citing the long product timelines of the companies that make them.

“We can do it technically, and we’re certainly speaking to smartphone manufacturers about it,” he says. “But it’s going to take someone big to get the infrastructure in place for everyday charging.”

Kumar agrees, noting that it took years for the Qi wireless charging now used in many smartphones to become mainstream.

“I think (wireless power) is realistic,” he says. “But it will be an evolution, not a revolution.”